Apparently Poincare suggested and Einstein adopted/proposed that all physical laws should remain unchanged in form after a Lorentz transformation. Do we know these are the only transforms that work or does the possibility exist that other transforms might also?? For example, if I ask the question "What transforms retain the form of Maxwell's equations in different frames?" Lorentz transforms is one answer; but is it the only one?? If any particular transform worked in one physical law and not another, would that hint at anything....is that even possible??